1. Field of the Invention
The present invention relates to a pump of an integrated brake system, and more particularly, to a pump applied to an integrated brake system, which generates a braking pressure using an electric motor as a power source depending on a brake pedal operation of a driver and vehicle conditions.
2. Discussion of Related Art
Recently, to increase fuel efficiency and to reduce emissions, hybrid vehicles, fuel cell vehicles, electric vehicles, etc. have been vigorously developed. These vehicles essentially include brakes, that is, brakes of brake systems installed therein. Here, a brake for a vehicle indicates a device which reduces a speed of a traveling vehicle or stops the vehicle.
General brakes of brake systems for vehicles include vacuum brakes which generate a braking force using suction pressure of an engine and hydraulic brakes which generate a braking force using hydraulic pressure.
Vacuum brakes are devices which provide a great braking force with a small force using a pressure difference between suction pressure of a vehicle engine and atmospheric pressure in a vacuum booster. That is, it is a device which generates an output much greater than a force applied to a pedal when a driver presses the pedal.
In conventional vacuum brakes described above, it is necessary to supply suction pressure of a vehicle engine to a vacuum booster to form a vacuum and thus fuel efficiency is reduced. Also, even when a vehicle stops, it is necessary to constantly drive an engine to form a vacuum. Also, since fuel cell vehicles and electric vehicles do not include an internal combustion engine, it is impossible to apply conventional vacuum brakes which amplify a pedal effort of a driver during braking. In case of hybrid vehicles, in order to increase fuel efficiency, it is necessary to provide an idling stop function when a vehicle stops. Accordingly, it is necessary to apply hydraulic brakes.
That is, as described above, it is necessary to perform regenerative braking to increase fuel efficiency in all vehicles. However, when a hydraulic brake is applied, the regenerative braking is easily performed.
Meanwhile, an electro-hydraulic brake system, a hydraulic type brake, is a brake system in which when a driver presses a pedal, an electronic control unit senses it and supplies hydraulic pressure to a master cylinder, thereby transferring braking hydraulic pressure to each wheel and generating a braking force.
Recently, integrated brake systems in which a pump, a control unit, and a valve which form an electro-hydraulic brake system are integrated in one module have been developed. Since the integrated brake systems described above are formed by integrating necessary units as one, products have large sizes and are inconvenient to be mounted in vehicles.
The following prior art document discloses a structure for preventing rotation of a ball screw bar of a steering device for a vehicle, in which the ball screw bar is restrained from rotating together with a motor when the motor rotates to prevent wheels from being degraded in performance but does not disclose technical features of the present invention.